How to insert the entry "parent relation"?

I-m using JOSM with the relation editor. How can I solve this?
greetings, wonk

You cannot add parent relations, instread you add a child member to the parent

thank you. But how do I add the child member to the parent?

Various ways are implemented.
One is : Open the parent relation in the relation editor, select the child so that it appears in the relation editor and click on of the buttons to move it to the wanted position in the member list.